A gas turbine engine generally includes a compressor section, a combustion section, and a turbine section. The compressor section progressively increases the pressure of air entering the gas turbine engine and supplies this compressed air to the combustion section. The compressed air and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected to a generator to produce electricity.
The turbine section generally includes a plurality of rotor blades, which extract kinetic energy and/or thermal energy from the combustion gases flowing through the turbine section. In this respect, each rotor blade includes an airfoil positioned within the flow of the combustion gases. Since the airfoils operate in a high temperature environment, it may be necessary to cool the rotor blades.
In certain configurations, cooling air is routed through one or more cooling passages defined by the rotor blade to provide cooling thereto. Typically, this cooling air is compressed air bled from the compressor section. Bleeding air from the compressor section, however, reduces the volume of compressed air available for combustion, thereby reducing the efficiency of the gas turbine engine.